1. Field of the Invention
The present invention relates to a pressure-difference regulating valve unit, a liquid cartridge and a method for assembling a liquid cartridge. More particularly, the present invention relates to a pressure-difference regulating valve unit, a liquid cartridge and a method for assembling a liquid cartridge, wherein the liquid cartridge supplies a liquid to a liquid ejecting apparatus when mounted on the liquid ejecting apparatus.
2. Description of the Related Art
In an inkjet type recording apparatus, ink is supplied to a recording head while mounting an ink cartridge containing the ink on a holder of an inkjet type recording apparatus. Here, the ink, the inkjet type recording apparatus and the ink cartridge are an example of the liquid, the liquid ejecting apparatus and liquid cartridge respectively.
The ink cartridge is provided with, for example, an ink accommodating section for containing the ink, a valve member that operates based on the pressure difference between the ink accommodating section side and the recording head side and an atmospheric valve for connecting the ink accommodating section with the atmosphere. This ink cartridge is mounted on a holder of an inkjet type recording apparatus, and thus the atmospheric valve allows the ink accommodating section to be connected with the atmosphere. Further, in the state where the ink cartridge is mounted on the holder, the pressure difference occurs in the valve member because the recording head consumes the ink, so that a center part of the valve member is elastically deformed by the pressure difference, and thus the ink is supplied to the recording head from the ink accommodating section as disclosed in Japanese Patent Application Publication No. 1999-170558.
In the ink cartridge above, the valve member has a peripheral edge part with the difficulty to be elastically deformed in contrast to the center part, and the peripheral edge part is fixed to the ink cartridge by ultrasonic welding. Therefore, there was a problem that the dust caused by ultrasonic welding was mixed into the ink.